Osu Castle — properly Fort Christiansborg — is the 17th-century Danish fort at Osu, Accra, that served as the seat of Ghana's government for most of the First Republic and again during the National Liberation Council era after the 24 February 1966 coup that overthrew Osagyefo Dr Kwame Nkrumah. The fort was begun by the Danes around 1659–1661 on land bought from the Osu (Christiansborg) people, and it changed hands repeatedly — Danish, Portuguese, Akwamu, British — before Britain took it permanently in 1850 and made it the seat of the Gold Coast colonial administration. When Ghana became independent in 1957, Nkrumah moved the seat of government into Christiansborg Castle, and it remained the office and residence of the head of state thereafter. That is why the NLC era matters. After the February 1966 coup, the National Liberation Council — led by Lt. Gen. Joseph Arthur Ankrah, with Emmanuel Kotoka, Akwasi Afrifa and others — governed from Osu Castle, exactly as Nkrumah had. The castle was the physical centre of state power through the NLC (1966–69), the Busia Progress Party government (1969–72), the Acheampong and Akuffo eras, the Rawlings AFRC and PNDC years, and every government up to the Fourth Republic. Its most famous Fourth Republic chapter came on 7 January 2009, when John Evans Atta Mills was sworn in at Independence Square rather than the castle — a deliberate break from the past. President John Dramani Mahama later moved the seat of government to the Flagstaff House (Golden Jubilee House) on the Airport City road, and Osu Castle was formally handed over to the Ministry of Tourism, Culture and Creative Arts in 2013 to be developed as a heritage and museum site. The castle sits on the UNESCO-listed Forts and Castles of Ghana, alongside Cape Coast and Elmina castles, and its dungeons were part of the transatlantic slave trade infrastructure. So the short answer: Osu Castle was the seat of government during the NLC era because it had been the seat of government since colonial times and Nkrumah kept it — the NLC simply inherited it, and Ghana's rulers governed from Christiansborg until the Flagstaff House era. Today it is a presidential-heritage property and museum-in-progress rather than the working seat of government. *Akan wisdom fits here: "Abofra bo nnwa na ɔnhu ne nsa" — the child cracks the snail and does not see the knife. Power changed hands many times at Christiansborg, but the building itself outlasted every regime that sat in it.*